Field of the Invention
The present invention relates to ultrasonic treatment apparatuses and, in detail, relates to an ultrasonic treatment apparatus which performs a surface treatment with an ultrasonic wave on a treatment target object immersed in treatment liquid.
Description of the Related Art
Conventionally, an ultrasonic treatment apparatus is used to clean treatment target objects such as electronic components and printed circuit boards. For example, a printed circuit board is subjected to various treatments such as a desmear treatment; however, there are attached foreign substances such as a resin and smears on the surface of the printed circuit board after treatments. To address this issue, the printed circuit board is immersed in treatment liquid, and an ultrasonic treatment is then performed by oscillating an ultrasonic wave so that a cavitation action will remove the foreign substances and the smears attached on the printed circuit board surface.
Conventionally there are pointed out problems occurring in association with an ultrasonic treatment, and there is proposed an ultrasonic treatment apparatus with which the problems are reduced. For example, when the treatment liquid is flowing by circulation or the like, it is difficult to perform a uniform treatment with an ultrasonic wave, being affected by the flow.
As a solution to the above problem, for example, JP-A-2000-107710 discloses an ultrasonic substrate treatment apparatus in which an ultrasonic wave is transmitted toward a boundary plate disposed between the treatment liquid in the treatment liquid bath and the atmosphere.